Annular modes in multiple migrating zonal jet regime

Recent studies have linked hemispheric climate variability to annular modes, zonally symmetric structures that describe the horizontal redistribution of atmospheric mass. The resulting changes in the pressure patterns consequently alter the atmospheric circulation, including the movement of zonal jets in the atmosphere. While the literature contains much observational evidence describing these annular modes, the fundamental dynamics in the perpetuation of the annular modes still remains poorly understood. We investigate the dynamics of the annular modes using the MITGCM, a semi-hemispheric ocean model. The forcings imposed in the model are an atmospheric wind stress and relaxation to a latitudinal temperature profile, which induces a baroclinically unstable flow. Despite such an idealized setup, the model output shows striking similarities to the observed atmospheric annular modes, where the leading mode of variability is associated with the primary zonal jet's meridional displacement. By convention, when the zonal jet is poleward (equatorward) of its time-mean position, the principal component (PC) of the first empirical orthogonal function (EOF) is positive (negative) and is referred to as the high (low) zonal index.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2006

Author dc:creator

• Chan, Cegeon J

Advisor dc:contributor.advisor

• R. Alan Plumb.

• Earth, Atmospheric, and Planetary Sciences.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/34569

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/34569